Can you show how IO::Pty could be used to modify the second program in the OP (the program with PIPE1 in it) so that it would process the output from blackbox.pl in real time (leaving blackbox.pl untouched)?

Regarding the "system dependent" issue, I am running Linux 7.3 with the 2.4.20-20.7 kernel. I gather from the docs for IO::Tty that I sould be okay in that respect.

Not pretty, and perhaps there are better ways, but this may get you started anyway:

#!/usr/bin/perl -w
use strict;
use IO::Pty;

my $pty = new IO::Pty;
my $slave = $pty->slave();

my $pid = fork();
die "Couldn't fork: $!" unless defined $pid;

if($pid){  # dup STDOUT to Pty and run external program:
    $pty->close_slave();
    open(STDOUT, ">&",$pty)||die $!;
    system "perl blackbox.pl";
    print "\cD"; # send ^d to end 

} else {    # this is your monitoring process
    $pty->make_slave_controlling_terminal();
    print "*$_" while <$slave>;
    exit;
}
__END__
[download]

Works for me on Linux.

There's also a snippet here that does this.

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